1、python文件进入交互模式的方法
import IPython
IPython.embed()
2、peewee模块的安装参考官网
3、peewee模型简单的结构：
Model class --> Database table
Field class --> Column table
Model instance --> Row in a database table
from peewee import *
db = SqliteDatabase('people.db')
class Person(Model):
name = CharField()
birthday = DateField() is_relative = BooleanField()
class Meta:
database = db
class Pet(Model):
owner = ForeignKeyField(Person, related_name='pets') name = CharField()
animal_type = CharField()
class Meta:
database = db
4、以sqlite3为例，先创建对应模型的数据表
>>> db.connect()
>>> db.create_tables([Person, Pet])
5、新添模型数据
方法一：
>>> from datetime import date
>>> uncle_bob = Person(name='Bob', birthday=date(1960, 1, 15), is_relative=True)
>>> uncle_bob.save()
方法二：
>>> p1 = Person.create(name='p1', birthday=date(1999, 10, 10), is_relative=True)
6、删除数据
>>> p1.delete_instance()
7.1、得到单一数据 get()
方法一：
>>> uncle_bob = Person.select().where(Person.name == 'Bob').get()
方法二：
>>> uncle_bob = Person.get(Person.name == 'Bob')
7.2、得到数据列表 select()
>>> query = Pet.select()
>>> query = Pet.select().where(Pet.animal_type == 'cat')
7.3、使用 join()
query = (Pet.select(Pet, Person).join(Person).where(Person.name == 'Bob'))
7.4、数据列表排序 order_by()
>>> query = Pet.select().where(Pet.owner == uncle_bob).order_by(Pet.name)
7.5、模型间数据关联
获取到属于person的pet的数目
>>> for person in Person.select():
... print(person.name, person.pets.count())
>>> subquery = Pet.select(fn.COUNT(Pet.id)).where(Pet.owner == Person.id)
>>> query = (Person.select(Person, Pet, subquery.alias('pet_count')).join(Pet, JOIN.LEFT_OUTER).order_by(Person.name))
7.6、获取条件范围的数据
>>> d1940 = date(1940, 1, 1)
>>> d1960 = date(1960, 1, 1)
>>> query = (Person.select().where((Person.birthday < d1940) | (Person.birthday > d1960)))
注：或条件使用 | ，且条件使用 &
7.7、获取Person的name首字母为g或G的数据
>>> expression = (fn.Lower(fn.Substr(Person.name, 1, 1)) == 'g')
>>> query = Person.select().where(expression)
7.8、关闭数据库
>>> db.close()
以下为简单的应用
8、模型数据结构和关系
database = SqliteDatabase(DATABASE)
class BaseModel(Model):
class Meta:
database = database
class User(BaseModel):
username = CharField(unique=True) password = CharField()
email = CharField()
join_date = DateTimeField()
class Meta:
order_by = ('username',)
class Relationship(BaseModel):
from_user = ForeignKeyField(User, related_name='relationships')
to_user = ForeignKeyField(User, related_name=' ')
class Meta:
indexes = (
# Specify a unique multi-column index on from/to-user.
(('from_user', 'to_user'), True),
)
class Message(BaseModel):
user = ForeignKeyField(User)
content = TextField()
pub_date = DateTimeField()
class Meta:
order_by = ('-pub_date',)
peewee中可使用的数据类型：
String、Integer、float、Decimal、Boolean、Date、time、datetime、None、Binary
9、创建表
def create_tables():
database.connect()
database.create_tables([User, Relationship, Message])
注：peewee内置有create_tables()方法，但是考虑到模型字段的变更，基本上不用，而是使用sqitch进行数据库版本变更管理。
10、flask框架中一般在请求前开启，响应后关闭数据库
@app.before_request
def before_request():
database.connect()
@app.after_request
def after_request(response):
database.close()
return response
11、查询
不是重点：
def following(self):
# query other users through the "relationship" table
return (User
.select()
.join(Relationship, on=Relationship.to_user)
.where(Relationship.from_user == self))
def followers(self):
return (User
.select()
.join(Relationship, on=Relationship.from_user)
.where(Relationship.to_user == self))
12、创建一个新对象
try:
with database.transaction():
# Attempt to create the user. If the username is taken, due to the
# unique constraint, the database will raise an IntegrityError.
user = User.create(username=request.form['username'],
password=md5(request.form['password']).hexdigest(),
email=request.form['email'],
join_date=datetime.datetime.now()
)
# mark the user as being 'authenticated' by setting the session vars
auth_user(user)
return redirect(url_for('homepage'))
except IntegrityError:
flash('That username is already taken')
13、<<为包含在的意思
messages = Message.select().where(Message.user << user.following())